Screw-nail



S. E. GEOFF. scnnw NAIL.

(No Model.)

No. 426,008. Patented Apr. 22, 1890.

UNITED STATES PATENT ()FFICE.

SYLVANUS E. GEOFF, OF MARIETTA, PENNSYLVANIA.

SCREW-NAI L.

SPECIFICATION forming part of Letters Patent No. 426,008, dated April 22, 1890.

Application filed April 2, 1889. Serial No. 805,764. (No model.)

To all" whom it may concern.-

Be it known that I, SYLVANUS E. GEOFF, a citizen of the United States, residing in Marietta, in the county of Lancaster and State of Pennsylvania, have invented certain Improvements in Screw-Nails, of which the following is a specification.

My invention relates to improvements in serewnails; and the object of my improvement is to produce a spirally-grooved nail,

"which shall rotate as it is driven into the wood, forufin g a corresponding tl'i'fe'ad tner'e in to prevent it from being withdrawn.

My invention consists in cutting or otherwise forming a number of spiral grooves in nails formed of cylindrical wire the entire length of the nail from a short distance be low the head to the point, which should be conical.

My invention is illustrated in the accompanying drawings, forming a part of this specification, in which Figure 1 is a vertical sectional view of a block of wood on the liney 3 Fig. 3, showing the nail in place, Fig. 2 is a similar view, but with the nail removed to show the threads formed in the wood. Fig. 3 is a transverse section on the line at as of Fig. 1.

In the drawings, A represents one of my nails driven into a block of wood B.

C C are spiral grooves cut in the surface of the nail and extending from a point a near the head of the nail to the point 1) thereof. The grooves are parallel with each other, and the lower ends Of all of them are open and terminate in the point of the nail, which is conical in shape, as shown in Fig. 1. The efiect of this construction is that as the nail is driven into the wood the grooves C 0 form threads d in the wood, which cause the nail to revolve as it is driven in, so as to preserve the continuity of the threads, and thus offer as much resistance to the withdrawal of the nail as though it were a screw. Vhen the the fibers thereof apart.

point of the nail is driven into the wood, the

lower ends of the grooves receive the parts opposite to them without crushing or forcing The nail progressing, this action continues, the fibers of the wood being received in the ends of the grooves, as they are successively brought opposite to them by the advance of the point of the nail, so that each groove formsa continuous and unbroken thread which remains engaged therein. The grooves are of such number that the threads formed by them have the strength necessary to produce a continuous rotary movement of the nail as it advanees.

I have been in the habit of cutting four grooves in each nail, as giving good results; but this number may be varied, though it is somewhat doubtful whether a less number would be certain to produce the necessary screw motion.

Fig. 2, in which the nail is removed, fully shows the spiral threads or ribs (1, formed by the grooves in the nail as it is driven into the wood.

I am aware that there are nails having a single groove or rib. These do not turn, but push through the wood, depending upon the elasticity of the wood to fill in the groove or about the rib and hold it in place.

Having thus described my invention, what I claim as new, and desire to secure by Let ters Patent, is

A screw-nail having a conical point and provided with parallel spiral grooves extending from the head to and terminating in the point, the grooves being of such number and so elongated as to rotate the nail and form threads in the wood as the nail is driven into the same, substantially as and for the purpose specified.

SYLVANUS E. GEOFF.

\Vitnesses:

CLAUDE L. GRoFF, J. J. MONIOHOLL. 

